The pristine swimming pool of a glamorous couple’s private villa in the French Riviera is the focus of Jacques Deray’s 1969 tale of lust, co-dependency and revenge. Of ample size and stylish design, it’s where lovers Jean-Paul (Alain Delon) and Marianne (Romy Schneider) fool around during a long hot summer, far from the madding crowd of St Tropez. It’s also where Jean-Paul challenges Marianne’s ex-lover Harry (Maurice Ronet) to a symbolic swimming race, and where the film reaches its shocking and deadly climax.

Even outside of the pool and sea, water – or lack of it – is a strong motif throughout the film. Jean-Paul is told he’s a ‘Pisces, with Aquarius rising, you were born to be loved’, while his decision to start drinking again after a teetotal patch will prove fatal. And when one character is killed, there is a noticeable lack of tears at their passing.

Harry’s nubile teenage daughter Penelope (Jane Birkin), whose arrival with her father brings Jean-Paul and Marianne’s peaceful holiday ‘&#224 deux’ to an end, isn’t seduced by the chlorinated blue of the pool. She’d rather idle around in modish thigh-skimming dresses, ignoring her father, who she claims is only interested in her now she’s old enough to be mistaken for his girlfriend. Better still, she likes swimming in the sea. And when Jean-Paul - who is not indifferent to her doe eyes and sky-high legs – takes her there for a night-time swim, he crosses the unspoken line of decency forever.

Deray does a deft job in capturing the hedonism and abandon of the period, where good looks and chic clothes conceal dark feelings that lurk beneath the surface, helped by a toe-tapping soundtrack by Michel Legrand. Legrand is a name often associated with the French New Wave, as is Maurice Ronet, who plays smooth-talking music producer Harry, but La piscine‘s connection with the movement ends there. Instead, with its smoulderingly attractive cast and focus on relationships, it owes more to American film noir and psychological thrillers of the previous two decades, as is especially clear after the pivotal murder scene – which is sudden, clumsy and disturbing.

While it may seem stilted to some, the lackadaisical pace of the film has the dual advantage of both reflecting the holiday-makers’ idle summer and allowing the unspoken erotic tension to reach a Hitchcockian crisis point. When the pace is broken by a lively and impromptu shindig, held at the villa by Harry and his rent-a-crowd of hipsters and kohl-eyed beauties, it comes as a relief to the viewer but has devastating consequences for the characters, who use it as an excuse to turn feelings into actions.

The film’s real strength lies in its ending which, although implausible by today’s standards of law and order, comes as a genuine surprise and shows the price you might have to pay to get simple domesticity.